The Molecular Systems Pathology Core will provide expert morphological evaluation of normal and tumor samples of human and mouse models to investigators of the Program Project. The Core will further develop novel technology in the areas of morphometry and image analysis of quantitative biomarker multiplexing in tissue sections. This Core is also generating new assays, such as those for analysis of DNA damage using H2AX quantitation at high spectral resolution, for studying senescence at the microanatomical detail, and ex vivo assays using fresh human prostate cancer specimens. Through such approaches, the Core will integrate with all three Projects in pursuing systems pathology approaches to investigate expression of NKX3.I (the major scientific goal of the Core), to study markers of prostate stem cells (Project 1), to examine the expression of direct transcriptional targets of NKX3.1 (Project 2), and to quantify DNA damage response markers in human and mouse prostate tissues (Project 3). We have ample tissue resources to assist all Projects, including a set of 140 human prostate tumors (training set), a second independent cohort of 410 human prostate tumors (validation set), as well as large and well characterized cohorts of human prostate cancer tissues from Memorial Sloan-Kettering Cancer Center (MSKCC) and the Genitourinary Program of the Southwestern Oncology Group (GU-SWOG). This Core also provides assistance in conducting immunohistochemical (IHC) and in situ hybridization (ISH) assays, including interphase fluorescence in situ hybridization (FISH). Using these resources, we will characterize expression patterns of known genes participating in pathways of relevance for the Program, as well as novel genes identified through studies conducted by the proposed projects. The specific aims are: (1) To investigate the occurrence and correlation of molecular alterations associated with prostate cancer initiation in human preneoplastic and tumor lesions, an aim that includes both technology development and further definition of the temporal map of molecular alterations associated with prostate cancer progression; (2) To examine the expression of NKX3.1 and stem/progenitor markers in androgen-ablated and hormonally-intact human prostate specimens, working with Michael Shen in Project 1; (3) To characterize the expression of NKX3.1 and its transcriptional targets identified in Project 2 using normal and tumor human specimens, working with Cory Abate-Shen; and (4) To further study the relationship of NKX3.I inactivation and the formation of TMPRSS2-ERG fusions, studying pre- and post-treated mice after DNA damage with Edward Gelmann in Project 3.